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package com.oracle.truffle.jx.runtime;

import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
import com.oracle.truffle.api.RootCallTarget;
import com.oracle.truffle.api.interop.TruffleObject;
import com.oracle.truffle.api.strings.TruffleString;
import com.oracle.truffle.jx.JanivaLang;
import java.util.*;

/** Manages the mapping from function names to {@link JXFunction function objects}. */
public final class JXFunctionRegistry {

  private final JanivaLang language;
  private final FunctionsObject functionsObject = new FunctionsObject();
  private final Map<Map<TruffleString, RootCallTarget>, Void> registeredFunctions =
      new IdentityHashMap<>();

  public JXFunctionRegistry(JanivaLang language) {
    this.language = language;
  }

  /**
   * Returns the canonical {@link JXFunction} object for the given name. If it does not exist yet,
   * it is created.
   */
  @TruffleBoundary
  public JXFunction lookup(TruffleString name, boolean createIfNotPresent) {
    JXFunction result = functionsObject.functions.get(name);
    if (result == null && createIfNotPresent) {
      result = new JXFunction(language, name);
      functionsObject.functions.put(name, result);
    }
    return result;
  }

  /**
   * Associates the {@link JXFunction} with the given name with the given implementation root node.
   * If the function did not exist before, it defines the function. If the function existed before,
   * it redefines the function and the old implementation is discarded.
   */
  JXFunction register(TruffleString name, RootCallTarget callTarget) {
    JXFunction result = functionsObject.functions.get(name);
    if (result == null) {
      result = new JXFunction(name, callTarget);
      functionsObject.functions.put(name, result);
    } else {
      result.setCallTarget(callTarget);
    }
    return result;
  }

  /**
   * Registers a map of functions. The once registered map must not change in order to allow to
   * cache the registration for the entire map. If the map is changed after registration the
   * functions might not get registered.
   */
  @TruffleBoundary
  public void register(Map<TruffleString, RootCallTarget> newFunctions) {
    if (registeredFunctions.containsKey(newFunctions)) {
      return;
    }
    for (Map.Entry<TruffleString, RootCallTarget> entry : newFunctions.entrySet()) {
      register(entry.getKey(), entry.getValue());
    }
    registeredFunctions.put(newFunctions, null);
  }

  public JXFunction getFunction(TruffleString name) {
    return functionsObject.functions.get(name);
  }

  /** Returns the sorted list of all functions, for printing purposes only. */
  public List<JXFunction> getFunctions() {
    List<JXFunction> result = new ArrayList<>(functionsObject.functions.values());
    Collections.sort(
        result,
        new Comparator<JXFunction>() {
          public int compare(JXFunction f1, JXFunction f2) {
            assert JanivaLang.STRING_ENCODING == TruffleString.Encoding.UTF_16
                : "SLLanguage.ENCODING changed, string comparison method must be adjusted accordingly!";
            return f1.getName().compareCharsUTF16Uncached(f2.getName());
          }
        });
    return result;
  }

  public TruffleObject getFunctionsObject() {
    return functionsObject;
  }
}
